Affinity-purification and identification of GrpE homologues from mammalian mitochondria.

We used affinity chromatography on DnaK columns to identify a mitochondrial GrpE homologue from bovine, porcine and rat liver mitochondria. The 24 kDa GrpE homologue bound specifically to the DnaK column and was not eluted with 1 M KCl but readily with 5 mM ATP. Sequence analysis of the bovine homologue (85 residues) revealed 42% positional identity to mitochondrial GrpEp from S. cerevisiae and about 30% identity to the bacterial counterparts. Thus, GrpE homologues from higher and lower eukaryotes are highly conserved.